PubMed Health⌕ Search

Biomedical subjects

H Merk

Publications and source records attributed to H Merk.

At least 19 recordsLinked to original sources
PubMed1992

[The effect of foreign-substance-metabolizing enzymes on skin diseases].

Multiple drug-metabolizing enzymes are located in the skin of animals and humans: cytochrome P-450, epoxide hydrases, transferases and reductases. The distribution of cytochrome P-450 in the skin is not homogeneous; rather, it is more active in the basal epidermis, keratinocytes of the hair follicle, and sebaceous cells. The activity of drug-metabolizing enzyme can be induced, but it can also be inhibited by multiple endogenous and exogenous compounds. These enzymes detoxify many xenobiotics, but if the balance is disturbed there is the risk that xenobiotics will be activated to highly toxic compounds, which are even involved in the pathogenesis of skin cancer. Recent results indicate that cytochrome P-450 isoenzymes are also involved in the pathogenesis of psoriasis and drug-induced skin diseases.

Animals↗
PubMed1991

Induction and inhibition of NAD(P)H: quinone reductase in murine and human skin.

The purpose of this study was to characterize the human cutaneous NAD(P)H: quinone reductase (NQR) activity by known inhibitors of different reductases and to compare it with the murine skin and liver NQR activity. This enzyme plays a major role in the defence of cells against oxygen stress because it inhibits the 1-electron reduction of quinones to semiquinones and their subsequent oxidation to quinones termed as quinone redox cycle. It belongs to the aromatic hydrocarbon-responsive (Ah) battery. This gene battery includes Cyp1a1 (cytochrome P-450 IA1), Cyp1a2 (cytochrome P-450 IA2) and Nmo-1 [NAD(P)H: quinone reductase]. In the skin cytochrome P-450 IA1-dependent activity is about 1-5% compared to the corresponding activity in the liver, whereas NQR has the same activity in skin and liver. NQR was determined in the cytoplasm of murine skin, liver, and human keratinocytes using 2,6-dichlorophenolindophenol as the substrate. The Ah-receptor binding compounds, such as coal tar constituents, or 3-methylcholanthrene induce cytochrome P-450-dependent activities such as aryl hydrocarbon hydroxylase or 7-ethoxyresorufin-O-de-ethylase and NQR, whereas butyl hydroxytoluol, which does not bind to the Ah receptor, induces only NQR. For inhibition studies several known inhibitors of dihydrodiol dehydrogenase, aldo-keto and carbonyl reductase activities were used. There was a similar pattern of inhibition of the basal and induced activity in all tissues investigated. Pyrazole, progesterone and phenobarbital did not inhibit, whereas dicoumarol, rutin and indomethacin inhibited NQR activity in murine skin and liver as well as in human keratinocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Effect of an anthralin-containing hydrocolloid dressing in psoriasis vulgaris].

We investigated the effect of hydrocolloid dressings on the clearing of chronic plaque psoriasis. In comparison to a short-contact therapy with anthralin alone, following application of a hydrocolloid dressing accelerated the clearing of the plaques. This effect was significant after 3 weeks of therapy. A considerable improvement was achieved by the application of a hydrocolloid dressing containing anthralin. For this purpose anthralin in concentrations of 0.02 to 0.20 mg/cm2 was applied to the dressing immediately after it had been solved in acetone. The acetone was evaporated, and the anthralin was left on the dressing in a homogenous layer. In our study, the difference to short-contact anthralin was significant after 1, 2, 3, and 4 weeks of therapy. We conclude that this new way of anthralin application is suitable for the treatment of psoriasis and has therapeutical as well as technical advantages over a treatment with anthralin ointments.

Adult↗
PubMed1989

[Systemic photochemotherapy (PUVA) in acanthosis nigricans maligna: regression of keratosis, hyperpigmentation and pruritus].

We report on a 60-year-old patient, who developed malignant acanthosis nigricans (MAN) with intense itching 2 years after a large-cell bronchial carcinoma had been diagnosed and found inoperable. The MAN became manifest at a phase of full clinical remission of the lung tumor, which had been treated with cytostasis (cisplatin, vindesine), high energy irradiation, and extirpation of the lymph node metastases. One year after onset of MAN, the lung tumor relapsed, accompanied by an elevated serum level of carcinoembryonic antigen (CEA). The patient was slightly obese, but not diabetic. The generalized MAN was treated with 18 exposures to systemic PUVA (photochemotherapy) over 9 weeks. The patient received 8-methoxypsoralene (8-MOP) orally and a total UVA dose of 52 J/cm2; the last exposure amounted to a maximum dose of 4 J/cm2. Under this treatment, the patient was completely relieved from tormenting pruritus; in addition, we observed significant regression of the pigmented keratoses as well as the intertriginous maceration.

Acanthosis Nigricans↗
PubMed1989

Colorimetric growth assay for epidermal cell cultures by their crystal violet binding capacity.

The application of a simple, rapid, and inexpensive colorimetric growth assay was tested for human epidermal cells subcultured in uncoated plastic dishes. Cell layers were incubated with a crystal violet (CV) solution (0.2% with ethanol 2% in 0.5 M Tris-Cl buffer, pH 7.8) for 10 min at room temperature. After rinsing with 0.5 M Tris-Cl (pH 7.8) the cell layer was dried and decolorized with a sodium-dodecylsulfate solution (0.5% with ethanol 50% in 0.5 M Tris-Cl, pH 7.8) for 60 min at 37 degrees C. The extinction of the supernatant was read at the absorption maximum of 586 nm. The protein content of attached cells as classical parameter for quantifying cell growth was strongly related to CV extinction with a correlation coefficient of r = 0.98. Furthermore, the subcellular protein binding qualities of CV were analyzed. The water-soluble protein fraction of cultured epidermal cells was separated by sodium-dodecylsulfate polyacrylamide gel electrophoresis and stained with CV. We found a staining pattern which was qualitatively very similar to that of Coomassie blue, however less intense. Keratin electrophoresis revealed an affinity of CV to the 48, 50, and 56 kD cytokeratins. In conclusion, this CV assay is a reliable and simple method for the monitoring of epidermal cell growth in cultures.

Cell Division↗
PubMed1989

[High-resolution real-time sonography in the diagnosis of Achilles tendon diseases].

The Achilles tendons of 114 selected patients were examined using a high-resolution linear scanner at 7.5 mHz in real-time mode. Twelve ruptures of Achilles tendons, 16 soft tissue tumours, 36 inflammatory and 27 degenerative alterations were sonographically scanned. The remaining patients were known to have normal findings. Clinical, radiographic and intraoperative findings were evaluated for comparison. The sensitivity of sonography was 87%. In all cases of Achilles tendon rupture the sonographic diagnosis proved correct. Our findings demonstrate the possibility of differentiating Achilles tendon alterations with high specificity and sensitivity via real-time sonography. Clinical examination of patients with lesions of Achilles tendon should always be followed by sonography.

Achilles Tendon↗
PubMed1989

[The value of sonography in the differential diagnosis of soft tissue tumors].

A total of 379 patients with soft tissue swellings of unclear aetiology underwent a prospective examination with a high-resolution linear scanner during an interdisciplinary study. We diagnosed 112 true soft tissue tumours, 42 peripheric soft tissue metastases, 34 lymph node metastases, 106 tumour-simulating diseases, 56 inflammatory diseases, and 29 vascular alterations. Eighty-eight per cent of the cases were given the correct differential diagnostic classification by means of sonography. Assessment of malignancy ist not possible by means of sonography.

Diagnosis, Differential↗
PubMed1989

[Studies of hip dislocation in twins].

An arbitrary series of twins is used to demonstrate that there is no increased morbidity from congenital dislocated hip joint in twins. A physiologic delay in ossification of the cartilaginously preformed parts of articulations is caught up during the first year of life. In addition, connection with pregnancy and birth is discussed and r recommendations for diagnosis and therapy using sonography are given.

Birth Weight↗